﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace 翻译姬;
public class 键盘Hook {

    public event KeyEventHandler KeyDownEvent;
    public event KeyPressEventHandler KeyPressEvent;
    public event KeyEventHandler KeyUpEvent;

    public delegate int HookProc(int nCode, Int32 wParam, IntPtr lParam);
    static int hKeyboardHook = 0; //声明键盘钩子处理的初始值
                                  //值在Microsoft SDK的Winuser.h里查询
    public const int WH_KEYBOARD_LL = 13;   //线程键盘钩子监听鼠标消息设为2，全局键盘监听鼠标消息设为13
    HookProc KeyboardHookProcedure; //声明KeyboardHookProcedure作为HookProc类型
                                    //键盘结构
    [StructLayout(LayoutKind.Sequential)]
    public class KeyboardHookStruct {
        public int vkCode;  //定一个虚拟键码。该代码必须有一个价值的范围1至254
        public int scanCode; // 指定的硬件扫描码的关键
        public int flags;  // 键标志
        public int time; // 指定的时间戳记的这个讯息
        public int dwExtraInfo; // 指定额外信息相关的信息
    }
    //使用此功能，安装了一个钩子
    [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
    public static extern int SetWindowsHookEx(int idHook, HookProc lpfn, IntPtr hInstance, int threadId);


    //调用此函数卸载钩子
    [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
    public static extern bool UnhookWindowsHookEx(int idHook);


    //使用此功能，通过信息钩子继续下一个钩子
    [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
    public static extern int CallNextHookEx(int idHook, int nCode, Int32 wParam, IntPtr lParam);

    // 取得当前线程编号（线程钩子需要用到）
    [DllImport("kernel32.dll")]
    static extern int GetCurrentThreadId();

    //使用WINDOWS API函数代替获取当前实例的函数,防止钩子失效
    [DllImport("kernel32.dll")]
    public static extern IntPtr GetModuleHandle(string name);

    public void Start() {
        // 安装键盘钩子
        if (hKeyboardHook == 0) {
            KeyboardHookProcedure = new HookProc(KeyboardHookProc);
            hKeyboardHook = SetWindowsHookEx(WH_KEYBOARD_LL, KeyboardHookProcedure, GetModuleHandle(System.Diagnostics.Process.GetCurrentProcess().MainModule.ModuleName), 0);
            //hKeyboardHook = SetWindowsHookEx(WH_KEYBOARD_LL, KeyboardHookProcedure, Marshal.GetHINSTANCE(Assembly.GetExecutingAssembly().GetModules()[0]), 0);
            //************************************
            //键盘线程钩子
            SetWindowsHookEx(13, KeyboardHookProcedure, IntPtr.Zero, GetCurrentThreadId());//指定要监听的线程idGetCurrentThreadId(),
                                                                                           //键盘全局钩子,需要引用空间(using System.Reflection;)
                                                                                           //SetWindowsHookEx( 13,MouseHookProcedure,Marshal.GetHINSTANCE(Assembly.GetExecutingAssembly().GetModules()[0]),0);
                                                                                           //
                                                                                           //关于SetWindowsHookEx (int idHook, HookProc lpfn, IntPtr hInstance, int threadId)函数将钩子加入到钩子链表中，说明一下四个参数：
                                                                                           //idHook 钩子类型，即确定钩子监听何种消息，上面的代码中设为2，即监听键盘消息并且是线程钩子，如果是全局钩子监听键盘消息应设为13，
                                                                                           //线程钩子监听鼠标消息设为7，全局钩子监听鼠标消息设为14。lpfn 钩子子程的地址指针。如果dwThreadId参数为0 或是一个由别的进程创建的
                                                                                           //线程的标识，lpfn必须指向DLL中的钩子子程。 除此以外，lpfn可以指向当前进程的一段钩子子程代码。钩子函数的入口地址，当钩子钩到任何
                                                                                           //消息后便调用这个函数。hInstance应用程序实例的句柄。标识包含lpfn所指的子程的DLL。如果threadId 标识当前进程创建的一个线程，而且子
                                                                                           //程代码位于当前进程，hInstance必须为NULL。可以很简单的设定其为本应用程序的实例句柄。threaded 与安装的钩子子程相关联的线程的标识符
                                                                                           //如果为0，钩子子程与所有的线程关联，即为全局钩子
                                                                                           //************************************
                                                                                           //如果SetWindowsHookEx失败
            if (hKeyboardHook == 0) {
                Stop();
                throw new Exception("安装键盘钩子失败");
            }
        }
    }
    public void Stop() {
        bool retKeyboard = true;


        if (hKeyboardHook != 0) {
            retKeyboard = UnhookWindowsHookEx(hKeyboardHook);
            hKeyboardHook = 0;
        }

        if (!(retKeyboard)) throw new Exception("卸载钩子失败！");
    }
    //ToAscii职能的转换指定的虚拟键码和键盘状态的相应字符或字符
    [DllImport("user32")]
    public static extern int ToAscii(int uVirtKey, //[in] 指定虚拟关键代码进行翻译。
                                     int uScanCode, // [in] 指定的硬件扫描码的关键须翻译成英文。高阶位的这个值设定的关键，如果是（不压）
                                     byte[] lpbKeyState, // [in] 指针，以256字节数组，包含当前键盘的状态。每个元素（字节）的数组包含状态的一个关键。如果高阶位的字节是一套，关键是下跌（按下）。在低比特，如果设置表明，关键是对切换。在此功能，只有肘位的CAPS LOCK键是相关的。在切换状态的NUM个锁和滚动锁定键被忽略。
                                     byte[] lpwTransKey, // [out] 指针的缓冲区收到翻译字符或字符。
                                     int fuState); // [in] Specifies whether a menu is active. This parameter must be 1 if a menu is active, or 0 otherwise.

    //获取按键的状态
    [DllImport("user32")]
    public static extern int GetKeyboardState(byte[] pbKeyState);


    [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
    private static extern short GetKeyState(int vKey);

    private const int WM_KEYDOWN = 0x100;//KEYDOWN
    private const int WM_KEYUP = 0x101;//KEYUP
    private const int WM_SYSKEYDOWN = 0x104;//SYSKEYDOWN
    private const int WM_SYSKEYUP = 0x105;//SYSKEYUP

    private int KeyboardHookProc(int nCode, Int32 wParam, IntPtr lParam) {
        // 侦听键盘事件
        if ((nCode >= 0) && (KeyDownEvent != null || KeyUpEvent != null || KeyPressEvent != null)) {
            KeyboardHookStruct MyKeyboardHookStruct = (KeyboardHookStruct)Marshal.PtrToStructure(lParam, typeof(KeyboardHookStruct));
            // raise KeyDown
            if (KeyDownEvent != null && (wParam == WM_KEYDOWN || wParam == WM_SYSKEYDOWN)) {
                Keys keyData = (Keys)MyKeyboardHookStruct.vkCode;
                KeyEventArgs e = new KeyEventArgs(keyData);
                KeyDownEvent(this, e);
            }

            //键盘按下
            if (KeyPressEvent != null && wParam == WM_KEYDOWN) {
                byte[] keyState = new byte[256];
                GetKeyboardState(keyState);

                byte[] inBuffer = new byte[2];
                if (ToAscii(MyKeyboardHookStruct.vkCode, MyKeyboardHookStruct.scanCode, keyState, inBuffer, MyKeyboardHookStruct.flags) == 1) {
                    KeyPressEventArgs e = new KeyPressEventArgs((char)inBuffer[0]);
                    KeyPressEvent(this, e);
                }
            }

            // 键盘抬起
            if (KeyUpEvent != null && (wParam == WM_KEYUP || wParam == WM_SYSKEYUP)) {
                Keys keyData = (Keys)MyKeyboardHookStruct.vkCode;
                KeyEventArgs e = new KeyEventArgs(keyData);
                KeyUpEvent(this, e);
            }

        }
        //如果返回1，则结束消息，这个消息到此为止，不再传递。
        //如果返回0或调用CallNextHookEx函数则消息出了这个钩子继续往下传递，也就是传给消息真正的接受者
        return CallNextHookEx(hKeyboardHook, nCode, wParam, lParam);
    }
    ~键盘Hook() {
        Stop();
    }
}
